1. Field of the Invention
The present invention relates to a card-feeding mechanism, and more particularly, to a card-feeding mechanism implemented in a printer for ID cards.
2. Description of the Prior Art
A card-feeding mechanism can be positioned at an input of a printer of ID cards to deliver cards into the printer. The card-feeding mechanism drives a roller beneath a card, and when a friction force between the card and the roller is greater than a friction force between stacked cards, the card can be delivered into the printer. Furthermore, there is a limiting device in the card-feeding mechanism for assisting the bottom card in moving into the printer and keeping other cards in their respective positions.
Please refer to FIG. 1, which is a card-feeding mechanism 10 according to the prior art. A limiting device 12 of the card-feeding mechanism 10 can keep all cards 11 over a bottom card 13 in their respective positions. A roller 14 is connected to a motor 15 that drives the roller 14 to rotate and move the bottom card 13 into the printer. Additionally, there is another roller 16 positioned on the other side of the limiting device 12, and connected to a motor 17. The roller 16 is capable of assisting the card 13 in passing through the limiting device 12 until the card 13 is completely inside the printer and is ready to be printed.
The roller 14 has a rubber surface for increasing a friction coefficient between the roller and the card 13. However, often an adhesive material is added to the roller 14 for improving the friction coefficient between the roller and the card 13, and thus, the roller 14 requires constant maintenance. In addition, there is only one roller 14 before the limiting device 12 to deliver the card 13, and so the transmission of the card 13 is not very smooth. Therefore, some printers include a sensor to detect whether a card has become stuck or if there is any other malfunction during operation.